1. Field of the Invention
This invention relates to an improvement of an exhaust gas recirculation control valve. In particular, the invention relates to the addition of a corrosion-resistant lining in the control valve designed to resist the corrosive action of exhaust gas condensate.
2. Description of the Prior Art
An exhaust gas control valve is a known device for use in controlling the rate of flow of that portion of engine exhaust being recirculated through the engine for further combustion.
Internal combustion engine exhaust contains quantities of lead halide, sulfuric anhydride and other compounds which, when dissolved in liquid condensate, form a highly corrosive mixture. This mixture tends to accumulate on the interior wall surfaces of the prior art exhaust gas control valves corroding the exposed surfaces.
The interior walls of the prior art control valves, besides their predilection for corrosion, enhance the action of the corrosive mixture by having rough surfaces and sharp corners to which the mixture could attach and accumulate.
The present invention alleviates many of the corrosion problems of the prior art control valves by lining the interior walls exposed to the gases with a corrosion-resistant, smooth-surfaced metal. The improved control valve is also designed such that the metal lining reduces the number of sharp corners and crevices where the corrosive mixture condensates might accumulate.